High power demountable tube



July 3o, 1935. L, A GEBHAVRD 2,009,444

HIGH POWER DEMOUNTABLE TUBE '3 ATTORNEY July 30, 1935. L. A. Gl-:BHARD HIGH POWER DEMOUNTABLE TUBE Filed March 29, 1933 3 Sheecs-Sheeifl 2 *ggg . IN V EN TOR. Qw/Vgu/w) A TTORNEY July 30, 1935. A GEBHARD 2,009,444

HIGH POWER DEMOUNTABLE TUBE Filed March 29, 1933 3 Sheets-SheetI 3 Irc-r- E 'T :L 0^/ g if EJE-:.11

l I l? /l Patented July 3o, 1935 `UN'ITED STATE-s (Granted underthe act of March"3r,f1883, as .1v amended' April 30, 1928; 370 .0."G.v757)-' My inventionv relates broadly to A'high power electron tubes and moreparticularly to ay construction of demountable high power' transmit# 'ting tube.

lOne of the objects of my invention is to provide an improved construction of high power demountable electron tube in which the -di'sassemblfand assembly ofthe parts Vofthe tube may be readily effected and elements within .the tube replaced, the tube reassembled and evacuated at relatively small cost. I

" Anotherv object of my 'invention istoprovide a' constructionl of Vdemountalole electrontube in which the cathode structure may be readily .ree newed'for extending the activev life ofthe tube.

Still another object of my invention is to provide a construction of high' power tube in which a `demountable cathode structure is provided with fluid cooling means for supporting the cathode element.. v j

.'Afurther object of vmy invention isto pro# vide aconstruction of demountable electron tube in which a pair of adjustable chucks are mountf ed in one end ofjthe tube structure. for sup,- porting the cathode and another removable chuck is disposed in 'the Vinsulatorat the opposite end of the tube for supporting the control grid electrode, the chuckseach being uid cooled kfor improving the efliciency of operation of the tube. A still further object of my'invention is to pro- Avide an improvedassembly for a cathode and control grid unit in a demountable electron tube.

Other yand further objects of my invention reside in van improved high power demountable electron K'tube structure asset forth 'more-fulls'7 fin the specification hereinafter following b y reference tothe accompanying drawings, in which: Figure 1 is a central vertical longitudinal sectional View of a tube constructed in accordance with Amy invention, the structure supporting the filaments and adjacent 'parts being shownfin elevation; Fig. 2 is a similar View in central vertical longitudinal sectional showing'the filament, the grid,V and the adjacent supporting structure in section; Fig; 3 isa sectional elevation taken on line 3 3 of Fig. 1; Fig. 4 is a transverse vertical section taken online 4-4 of Fig. 2 looking inthe direction ofthe arrows; Fig. 5 is a bottom plan view of the tube; Figs. 6, '7, 8 and' 9 held together .byf'means of Vrivets l3- and 13'. r

are detailed horizontalsectional `views taken on correspondingly designated lines of Fig. 1;fFig. 10 is a' detailed frontelevation ofthe loop shaped memberused to connectthe filaments in series; Fig. llis a side elevation thereof; and Fig. 1 2 v5 is a top plan'view thereof. t

Ina demountable vacuum tube, it is desirable to have the lament structure so arranged that it can be quicklyand easily replaced. The cost of replacing'the filament mustY be low compared with the costof constructing a vacuum tube which is Vriot demountable in o-rder .to meet the economic requirements inthe` use ofl the demountabletube construction. iIt is also desirable to maintainthe number o f lairtight jointsat a minimum so as to reduce fthe 'possibilitiesl'for excessive vair leakage. These joints should'beas simple as possible; The insulating materialnecessarybetween the elements ofthe tube shouldhave suchv composition as will give'low loss" at high frequencies and, in addition, the structure should be Vof such texture a'sto insure tight joints. The insulating material should be so disposed, that excessive losses due to high intensity electric fields are avoided'and that voltage breakdown isV avoided. l These desirable points are all incorporated in the tube structure of my invention. 1 1 The lamentf structure. consists of Vtwo U `shaped 1 oops' of wire vsuch as tungsten, I and l',

.connected in'series and to terminal members 2 and 0 2f'. The two' loops are' supported at their upper ends by insulating member 3 which has a circular flange through which the/ filament wire passes. Insulator I3 is 'supported from fthe upper end of rod 4 which issupportedfrom its lower end as will `be described hereinafter. A shoulder 4" on rod 4 .appropriatelyseats' insulator." 3 on the vertical r'odA.r The two loops'areconnected'in series by Athe use of r1.hook-shaped'member 5 which is sup.-

ported-from rod 4 at a point 6 near V its lower end. .10

'bers 4 and 5 are4 held together byA means of a wire 45 wrapping, as shown at'B. ."Aclamp is provided at the` lower end of the filamentpstructure so as to make a rigidv unitwhich' can easily behandled. The clamp consists fof .two metal members Il and Sheaves of insulating material I4 and I4' are provided to prevent short-circuiting the filament circuit. Rod 4 is supported in the middle of this clamp.

y The lower ends of the filament connections 2 and 2' project beyond the clamp, as shown at I5, into chucks. These chucks consist of central members I 6 which are partially split radially and are embraced by nut members |1, causing the chucks to firmly grip the ends of the filament connections. Nut members |1 are provided with recesses, as shown at |8,Yso that a special Spanner Wrench may be inserted for tightening. Members I6 form part of the filament terminals and airtight joints. The ends I9 and |9' of the terminals are threaded to take nuts 20 and 2|, 20 and 2|'. Washers 22 and 22' are provided toprevent'excessive localized strains. The filament terminals are supported in cup-shaped insulating member 23. The points of support are also airtight joints, as shown at 24 and 24. These joints are conical in shape and are appropriately ground to insure against air leakage. Preferably, la suitable compound is placed on the surfacebefore assembly' to insure air-tightness. The circular boss 22a of insulator 23 is raised and ground to prevent'exces-V sive-mechanical stresses from being set up in the insulating material due to tightening up the terminals. TheV connections of the external circuit to the filament terminals are shown at 25 and 25. The filament terminals and airtight joints are simultaneously Water-cooled by the'same cooling system. This is accomplished by making the filament terminals hollow, providing chambers 26 into which tubes 21 and 21 project. Tubes 28 and 28' are mounted in the endof these charnbers. Caps 29 serve to close off the end ofthe chambers and to confine the tubes;fr The inner ends 3D of the tubes 21 areV centralized by bending with respect to the inner ends ofthe chambers 26. A cooling liquid is passed into tubes 21 and 21', driven against the inner end of the chamber and by the side walls to the outer vend of the chamber to be discharged through tubes 28 and 28'. Thus, the filament terminals, as well as thejoints, are

kept cool. The grid structure is supported from cupshaped insulating member 3| through airtight joint 32 which is constructed similar to those of the filament terminals; A boss .33'has a ground surface engaging'with washer 34 held by nut 35. Nut 33 holds lead 31 to the grid terminal. A threaded member 38 is engaged by the nuts 35 and 3b.V The grid terminal is liquidcooled in a manner similar to that ofthe filament terminals by the use of tubes 39 and 4|)k and the cap 4|. The, grid proper consists of a wire spiral 42 welded to longitudinal rods 43. Rods 43 are fitted at their upper kends in recesses in member 44 and Welded thereto 'pletes chamber 50. Joints are made at 5|. The

outer cylinder 5I can either be rolled as a sheet metal member around 4the cylindrical member 49 and soldered at the ends 5|' thereof as illustrated, or one or both of the frusto-conical ends of cylindrical memberj49 may beof sufficiently reduced diameter as to permit outer cylindrical tightening the joint.

member 5| to be telescopically slipped thereover in the nature of a sleeve and soldered in place. The cooling liquid enters through tube 52 and divides at joint 53 to pass through tubes 54 and 55. Tubes 54 and 55 are fastenedto and pass through member 5| so that the cooling liquid enters the recess 50 adjacent to the airtight joints 56 and 56 between insulating members 23 and 3| and the anode structure. This keeps the joints reasonably cool since the cooling liquid has not yet been heated by the anode. The liquid passes around the recess and toward the center and is discharged through tube 51. The airtight joints 56V and 5S are formed in a manner similar to that of the lament terminals, that is frustoconical surfaces are disposed in abutting contact with respect to each other. An anode terminal is shown at 49'.4

The connection to the vacuum pump is made by the'use of a conical shaped joint 58 which is similar in construction to the filament terminal joints. A washer 59 and nut 6|) are provided for A bore 6I passes up the centerY of the joint. The end `62 is appropriately connected to the vacuum pump.

In orderto provide low radio frequency loss and airtight joints, the insulating material used in the vacuum tube of Amy invention preferably has, as its mainconstituent, magnesium silicate or a combination of magnesium andj aluminum silicates. This material, when mixed with a suitable binder in suitable proportions and properly heat treated, .has a very close non-porous structure which permits making ,a good airtight joint. Parts of the inner and outer surfaces,lwhich are not ground, are covered with a suitable glaze to `int'o .insulator 23 andl inserted in the holes I8 in members I1 and the chucks holding the ends of the filament structure are loosened. This permits removing the filament structure and substituting a new one. The' chucks are tightened, the tube assembled and evacuated and is now ready for operation. l

- It will be observed that the ground frusto conical portions on the insulators establish rm surface contact over a large area of ground frusto conical portions of the uid cooled cylindrical anode which insures, an airtight seal. It will also be seen that the looped structure of the cathode provides for a substantial area of electron lemission from the cathode. At the same time, substantialcooling is effected by virtue of the arrangement of fluid cooled chucks in the insulator yat one end of the tube. A high degree of insulation is maintained between the control grid and the cathode structure and the control grid cooled by the continuous passage of cooling uid through the support for the control grid carried in the insulator at the otherend of the tube. The continuous coolingof the cylindrical anode which forms the enclosing vessel for the tube also insures high operating eiciencyin the tube. The

manner of insulatingly mounting theA cathode elements with respect to the control grid and concentrically disposing the cathode Velements and control .grid within they anode yfacilitates vthe assemblyand disassemblyof the elements of the tube while preventing electrical breakdown.

The tube structure of my invention provides an economical means of maintaining high power transmission systems in operation inasmuch as the number oi spares may be reduced to a minimum and a renewal tube substituted for a burned out tube while repair is being made of the burned out tube without the necessity of purchasing new tubes of large cost.

While I have described my invention'in certain of its preferred embodiments, I desire that it be understood that modications may be made and that no limitations upon my invention are intended other than are imposed by the scope of the appended claims.

The invention herein described may be manufactured and used by or for the Government of the United States of America for governmental purposes Without the payment of any royalty thereon or therefor.

What I claim as new and desire to secure by Letters Patent of the United States is as follows:

1. A high power electron tube comprising a cylindrical anode, frusto-conical end portions on said cylindrical anode, end members of insulation material each having a frusto-conical annular face disposed interiorly thereof in coacting relation to the frusto-conical end portions of said anode, an electrode removably mounted in one of said end members and projecting centrally within said anode, another electrode removably mounted on the other of said end members and projecting through said anode in a position concentric with the aforesaid electrode, and insulating means disposed between said first mentioned electrode and the opposite end member for maintaining said electrode in predetermined spacial relation with respect to said anode.

2. A demountable high power electron tube comprising a tubular iiuid cooled anode structure, irusto-conical end portions on said anode structure, cup-shaped end members of insulation material, annular frusto-conical surfaces disposed interiorly of each of said cup-shaped end members and coacting with the frusto-conical end portions on said anode, a pair of expansible and contractible chuck devices carried by one of said cup-shaped members, a cathode structure removably mounted in said chuck devices, a re-` movable supporting device carried by the other of said cup-shaped end members, a control grid carried by said removable supporting device, and means for fluid cooling said chuck devices and said supporting device.

3. A high power electron tube comprising a tubular fluid cooled anode structure, frusto-conical end portions on said anode structure, cupshaped end members of insulation material, annular frusto-conical surfaces disposed interiorly of each of said cup-shaped end members and coacting with the frusto-conical end portions on said anode, a pair of expansible and contractible chuck devices mounted in spaced relation in one of said cup-shaped end members, means for iluid cooling each of said chuck devices, a cathode structure removably mounted in said chuck devices and projecting interiorly of said anode, a supporting member removably mounted in the other of said cup-shaped end members, means for fluid cooling said supporting member, and a control grid carried by said supporting member and'projecting interiorly of said anode in a position concentrically disposed ,with respect to said cathode structure. i L vhigh powerelectron tube comprisinga tubularfuid! cooled anodestructure, frusto-conicalend portions onsaid anode structure, cupshaped end members of insulation material, annular frusto-conical surfaces disposed interiorly of each of said cup-shaped end members and coacting with the frusto-conical end portions on said anode, a pair of expansible and`contractible chuck devices mounted in spaced relation in one of said cup-shaped end members, means for uid cooling each of said chuck devices, a cathode structure removably mounted in said chuck devices and projecting interiorly of said anode, a supporting member removably mounted in the other of said cup-shaped endmembers, means for fluid cooling said supporting member, a control grid carried by said supporting member and projecting interiorly of said anode in a position concentrically disposed with respect to said cathode structure, and insulation means` disposed between said cathode structure and said supporting member for maintaining said cathode structure and control grid at predetermined spacial relation.

5. A high power electron tube comprising a l tubular anode, frusto conical end'portions on said anode, cup-shaped end closures each having an annular frusto conical surface engaging the frusto conical end portions of said anode, a pair of expansible and contractible chuck devices disposed in spaced relation in one of said cup- .shaped end closures, a member removably mounted in each of said chuck devices, a cathode structure supported by said members and extending interiorly of said anode, a removable supporting device carried by the other of said cup-shaped end closures, and a control grid mounted on said supporting device and extending interiorly of said anode in concentric relation to said cathode structure and said anode.

6. A cathode structure for a high power tube comprising in combination a pair of removable Supporting devices', a conductor removably supported in each of said devices, a bridge member insulatingly suspended between said conductors, a rod insulatingly supported by said bridge member and projecting intermediate said conductors,

a conductive member mounted on said rodimmediately above said bridge member, an insulating member carried by the upper end of said rod, and a pair of iilament members carried by said insulating member, one end of each lament connectedY to said conductive member, the other ends of the filaments connected to said conductors.

'7. A cathode structure for a high power tube comprising in combination with a pair of supporting devices, a conductor mounted in each of said devices, a bridge insulatingly suspended between said conductors, a rod insulatingly supported by said bridge intermediate said conduc-4 tors, a hook-shaped member carried by said rod immediately above said bridge, a flange carried by said rod adjacent the other end thereof, and a cathode connected at its opposite ends with said conductors and looped around said flange and said hook-shaped member for providing a double F looped cathode structure.

8. A cathode structure for a high power tu comprising in combination with a pair of supporting devices, aV conductor mounted in each of said devices, a bridge insulatingly suspended between said conductors, a. rod insulatingly supcathode structure and an insulating member car-v ported by said bridge intermediate said conducried by the upper extremity of said rod coacting tors, a member carried by said rod adjacent each to position said rod in positive spaced relation endtthereof, a cathode having its opposite ends with respect to other elements of said tube.

' 5 connected with said conductors and looped around 6 said members for providing a double looped LOUIS A. GEBHARD. 

